selftests/bpf: Stop using static variables for passing data to/from user-space

In preparation of skipping emitting static variables in BPF skeletons, switch
all current selftests uses of static variables to pass data between BPF and
user-space to use global variables.

All non-read-only `static volatile` variables become just plain global
variables by dropping `static volatile` part.

Read-only `static volatile const` variables, though, still require `volatile`
modifier, otherwise compiler will ignore whatever values are set from
user-space.

Few static linker tests are using name-conflicting static variables to
validate that static linker still properly handles static variables and
doesn't trip up on name conflicts.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210507054119.270888-4-andrii@kernel.org

1 files changed, 3 insertions, 3 deletions

diff --git a/tools/testing/selftests/bpf/progs/test_rdonly_maps.c b/tools/testing/selftests/bpf/progs/test_rdonly_maps.c
index ecbeea2df259..fc8e8a34a3db 100644
--- a/tools/testing/selftests/bpf/progs/test_rdonly_maps.c
+++ b/tools/testing/selftests/bpf/progs/test_rdonly_maps.c
@@ -5,7 +5,7 @@
 #include <linux/bpf.h>
 #include <bpf/bpf_helpers.h>
 
-static volatile const struct {
+const struct {
 	unsigned a[4];
 	/*
 	 * if the struct's size is multiple of 16, compiler will put it into
@@ -15,11 +15,11 @@ static volatile const struct {
 	char _y;
 } rdonly_values = { .a = {2, 3, 4, 5} };
 
-static volatile struct {
+struct {
 	unsigned did_run;
 	unsigned iters;
 	unsigned sum;
-} res;
+} res = {};
 
 SEC("raw_tracepoint/sys_enter:skip_loop")
 int skip_loop(struct pt_regs *ctx)